Circuit interrupter



INVENTOR WinthropMLeeds. am i) ATTORNEY? W M LEEDS CIRCUIT INTERRUPTER Feb. 3, 1953 Filed May 18, 1950 Flg I.

Feb. 3, 1953 w. M. LEEDS CIRCUIT INTERRUPTER Filed May 18, 19 50 2 SHEETSSHEET 2 INVENTOR WITNESSES:

Winthrop M.Leeds.

jaw) BY mm W Patented Feb. 3, 1953 CIRCUIT INTERRUPTER Winthrop M. Leeds, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa-., a corporation of Pennsylvania Application May 18, 1950, Serial No. 162,657

6 Claims.

pended to one end of two terminal bushings immersed in a suitable extinguishing liquid, an improved interrupting structure is appended to the lower end of the other of the two terminal bushings, an improved fluid conduit means is employed hydraulically interconnecting the two units and operatively associated with the operating rod.

Another object of the invention is to eliminate the possibility of electrical creepage breakdown across an oil flow conduit bridging the breaker terminals by having the conduit movable to a position disconnected from the terminals.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

Figure 1 is a side elevational view, partially in vertical section of a circuit interrupter embodying my invention and shown in the closed circuit position;

Fig. 2 is an enlarged vertical sectional view through the circuit interrupter of Fig. 1, the contacts being shown in the partially open circuit position;

Fig. 3 is a sectional view taken along the line III-III of Fig. 2 looking in the direction of the arrows; and

Fig. i is a vertical sectional view through a modified type of circuit interrupter embodying my invention and shown in the fully open circuit position.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral l designates a tank filled to the level 2 with a suitable arc-extinguishing fluid 3, in this instance circuit-breaker oil. Depending from the cover i are two terminal bushings 5, 6 to the lower ends of which are respectively appended a pressure-generating arc-extinguishing unit generally designated by the reference numeral 1 and an interrupting arc-extinguishing unit generally designated by the reference numeral 8.

Electrically interconnecting the two units 7, 8 is a conducting cross-bar 9 vertically reciprocally actuated by an insulating operating rod 10. In this instance, the operating rod [0 comprises two vertically extending operating members I I, I2 between which slides an insulating conduit tube 13. Preferably, the lateral sides of the tube 13 are milled out, as at It in Fig. 3, to provide a groove which keeps the axis of tube l3 horizontal by the guiding action of the operating members H, 12.

A knccker i5 is disposed between the operating members H, [2 being rigidly secured thereto by bolts 15, the purpose for which will appear more clearly hereinafter. Also disposed between the operating members ll, 12, at the lower ends thereof and positioned above the cross-bar 5, is a bumper [1, the purpose for which will also appear more clearly hereinafter.

The pressure-generating arc-extinguishing unit 1 includes a stationary contact structure l8 cooperable with the upper end iii of the crossbar 5! to establish a pressure-generating are 29 therebetween. The pressure-generating are 29 reacts upon the oil which completely fills the unit l to form gas. The formed gas will force oil out of the pressure-generating chamber 21 through the conduit tube I3 and into the interrupting arc-extinguishing unit 8.

The arc-extinguishing unit 8 includes a stationary contact structure 22 which cooperates with the right-hand upper tip 23 of the cross-bar 9 to establish an interrupting are 24 within an interrupting chamber generally designated by the reference numeral 25.

The interrupting chamber 25 is formed by the suitable disposition of a plurality of insulating plates placed in contiguous relationship and held together by insulating tie rods 25a. There are utilized essentially three different types of plates, the configuration of which is more clearly apparent from an examination of Figs. 2 and 3. The first type of plate is herein termed an insulating inlet plate 26 and has the configuration more clearly shown by the full lines in Fig. 3. As shown, the plate 26 has a cutout portion 21 removed therefrom to thereby provide two inlet passages 28. Immediately adjacent to the inlet plate 25 is an insulating orifice plate designated by the reference numeral 29 in Fig. 2. The orifice plate 29 has provided therein a pair of kidneyshaped openings 30 and a centrally disposed aperture 3! through which the movable interrupting contact 23 moves. Adjacent each insulating ori fice plate 29 is an insulating vent plate 32 of composite construction. The vent plate 32 comprises two laterally spaced half-plates 33, 34, which by their lateral separation provide two oppositely disposed vent passages 35. Certain features of the interrupter are described and claimed in my copending application filed May 18, 1950, Serial No. 162,655, and assigned to the assignee of the present invention.

The operation of the interrupter of Figs. 1-3 will now be explained. During the opening operation, the operating rod in is moved downwardly by suitable mechanism not disclosed, but which is responsive to manual operation or to the existence of overload conditions in the circuit controlled by the interrupter. The downward opening movement of the operating rod 10 also causes downwardly opening movement of the contacts 19, 23 to establish simultaneously a pressure-generating arc'20 within the pressure-genof frictional inserts 36 or rubber or other fric-' tional material. Consequently, oil under pressure formed. within the pressure-generating chamber 2i flows through the tube l3 in the direction of the arrows into the multi-orifice interrupting chamber 25. Here the oil flows through the plurality of inlet passages 23 to pass through the apertures or orifices 3| provided by the orifice plates 29, into intimate contact with the interrupting arc 24, to exhaust out of the interrupting unit 8 through the oppositely disposed vent passages 35 provided by the several vent plates 32.

Extinction of the interrupting are 25- soon follows, and continued downward opening movement of the operating rod It causes the knocker i5 to strike the top of the conduit 13 forcing the latter downwardly out of frictional holding engagement with the frictional inserts 36 to its fully open circuit disconnect position indicated by the dotted lines 3'? of Fig. 1. Naturally, after it has once been freed from the frictional inserts 36, it will slide downwardly between the operating members i i, it by its own weight until it reaches the position 3'? of Fig. 1.

Thus, in the fully open circuit position of the interrupter, the contacts i9, 23 are completely withdrawn from the units 7, 8, and the conduit i3 is also separated from the units 1, 8 so that no insulating path susceptible to creepage breakdown is present between the two units.

Oil circuit breakers of the self-generated flow type have not used insulating flow tubes bridging terminals of opposite potential at voltage ra ings above 15,000 volts because of the possibility of creepage breakdown when voltage is maintained for considerable periods of time with the contacts in the open position. My invention, as disclosed above, describes a removable oilfiow conduit i3 whichis only in place bridging the breaker terminals 5, 6 when the contacts are closed and during the initial part of the opening stroke. In the fully open position, the tube l3 ispulled down to a disconnect position 3'1, as shown in Fig. 1.

The tube i3 is held upwardly by friction and inertia until the knocker l5 strikes it and dislodges it near the end of the opening operation. During the closing operation, the bumper H on the contact cross-bar 9 picks up the tube 13 and forces it back into place between the frictional inserts 3%, at which time the contacts It, i9 and 22, 23 are engaged to thereby complete the electrical circuit passing through the interrupter.

For higher power breakers, ametal conduit may be used to join metal castings on the lower ends of the grids. Such a construction is shown in Fig. 4 in which a lower casting 38 is associated with the pressure-generating are-extinguishing unit l, and a lower casting 39 is associated with the interrupting arc-extinguishing unit 3. The metallic conduit or tube it has lips 3| formed on the ends thereof which engage slotted brackets 2 provided at the lower ends of the castings 38, 39 to thereby hold the metallic tube it fixedly in place with the open ends thereof in register with apertures 43 provided in the castings 33, 39.

Preferably, tension springs 44 are provided to bias the tube 593 upwardly into place between the units 1, 8. The upper ends of the tension springs :14 are secured to stationary supports 45, which preferably have rollers t5, the latter serving to guide downward motion of the operating rod 16.

As before, the operating rod ll! has associated therewith two operating members ll, [2 straddling the conduit All, and having a bumper I! and a knocker l5 associated therewith.

It will be noted that the lips 4!, when once wedged into place between the slots 37, prevent the units 1, 8 from being forced apart by the internal pressure present within the pipe 49. It will also be noted that the springs 64 bias the conduit ii) in place at a time when the contacts i9, 23 are just entering the grids l and B on the closing stroke.

The operation of the modified type of interrupter set forth in Fig. 4 is believed to be clear from the foregoing description. During opening, the operation is the same as thatset forth in connection with Fig. 2. During the closing operation, the springs d bias the conduit ll] into place between the brackets :12 while the contacts is, 23 are entering respectively the grids i, 8 instead of later just before reaching the fully closed position as in Fig. 2. Having the conduit ii! in place early is an advantage if the breaker should be tripped very rapidly when closing into a fault.

From the foregoing description of two embodiments of my invention, it will be apparent that I have provided an improve-:1 liquid break type of circuit interrupter in which a pressure-generating chamber construction is disposed at the lower end of one terminal bushing and an interrupting arcextinguishing structure is disposed at the lower end of the other terminal bushing. It will be apparent that I have provided improved fluid conduit means interconnecting the two units, which conduit means is forcibly removed from between the units near the end of the opening operation of the interrupter, to thereby eliminate voltage stress between the .units and to prevent creepage breakdown along insulating surfaces.

Although I have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A circuit interrupter of the liquid break type including a tank containing an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior ends of the terminal bushings, a pressure-generating chamber secured to the interior end of one terminal bushing, an interrupting chamber secured to the interior end of the other terminal bushing, a pair of movable contacts engaging the pair of stationary contacts in the closed position, said movable cont-acts establishing a pressure-generating are within the pressure-generating chamber and an interrupting are within the interrupting chamber during the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar, a liquid conducting tube separate from the cross-bar and hydraulically interconnecting the two chambers during a portion of the opening operation, the tube being momentarily stationary during this time whereas the movable contacts move relative thereto to establish arcing with the stationary contacts, and means for moving the tube to a position away from the chambers near the end of the opening operation of the interrupter.

2. A current interrupter of the liquid break type including a tank containing an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior ends of the terminal bushings, a pressure-generating chamber secured to the interior end of one terminal bushing, an interrupting chamber secured to the interior end of the other terminal bushing, a pair of movable contacts engaging the pair of stationary contacts in the closed position, said movable contacts establishing a pressure-generating are within the pressure-generating chamber and an interrupting are within the interrupting chamber during the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar, a liquid conducting tube separate from the cross-bar and hydraulically interconnecting the two chambers durin :a portion of the opening operation, the tube being momentarily stationary during this time whereas the movable contacts move relative thereto to establish arcing with the stationary contacts, the tube being away from the chambers near the end of the opening operation of the interrupter, and means biasing the tube toward its closed circuit position.

3. A circuit interrupter of the liquid break type including a tank containin an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior ends of the terminal bushings, a substantially confined pressure-generating chamber secured to the interior end of one terminal bushing, a separate vented interrupting chamber secured to the interior end of the other terminal bushing, a pair of movable contacts engaging the pair of stationary contacts in the closed position, said movable contacts establishing a pressure-generating are within the pressure-generating chamber and an interrupting arc wiithin the interrupting chamber during the initial portion of the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar, and a movable liquid conducting tube hydraulically interconnecting the two chambers during a portion of the opening operation and having a lost-motion connection with respect to the cross-bar.

4. A circuit interrupter of the liquid break type including a tank containing an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior ends of the terminal bushings, a pressure-generating chamber secured to the interior end of one terminal bushing, an interrupting chamber secured to the interior end of the other terminal bushing, a pair of movable contacts engaging the pair of stationary contacts in the closed position, said movable contacts establishing a pressure-generating are within the pressure-generating chamber and an interrupting are within the interrupting chamber during the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar and having a knocker thereon, a liquid conducting tube separate from the cross-bar and hydraulically interconnecting the two chambers during a portion of the opening operation and forced therefrom by the knocker near the end of the opening operation of the interrupter, the tube having lips at the ends thereof, and each chamber having at the lower end thereof a slotted portion into which the lips fit during the closed position of the interrupter.

5. A circuit interrupter of the liquid break type including a tank containing an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior end of the terminal bushings, a pressure-generating chamber secured to the interior end of one terminal bushing, an interrupting chamber secured to the interior end of the other terminal bushing, a pair of movable contacts engaging the pair of stationary contacts in the closed position, said movable contacts establishing a pressure-generating arc within the pressure-generating chamber and an interrupting are within the interrupting chamber during the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar, a liquid conducting tube separate from the cross-bar and hydraulically interconnecting the two chambers during a portion of the opening operation and forced therefrom by movement of the operating rod near the end of the opening operation of the interrupter, the tube having lips at the ends thereof, and each chamber having at the lower end thereof a slotted portion into which the lips fit durin the closed position of the interrupter, and means biasing the tube toward its closed circuit position.

6. A circuit interrupter of the liquid break type including a tank containing an arc extinguishing liquid, a pair of spaced terminal bushings extending within the tank, a pair of stationary contacts secured to the interior ends of the terminal bushings, a substantially enclosed pressure-generating chamber secured to the interior end of One terminal bushing, a substantially enclosed interrupting chamber secured to the interior end of the other terminal bushing, a pair of rod-shaped movable contacts engaging the pair of stationary contacts in the closed position, said movable contacts establishing a pressure-generating are within the pressure-generating chamber and an interruptin are within the interrupting chamber during the opening operation, a conducting cross-bar interconnecting the two movable contacts, an operating rod actuating the cross-bar and having a knocker thereon, and a liquid conducting tube separate from the cross-bar and hydraulically interconnecting the two chambers during a portion of the opening operation and forced therefrom by the knocker near the end of the opening operation of the interrupter, the operating rod comprising two elongated members, and the tube sliding between the members.

WINTHROP M. LEEDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,530,444 Trencham Mar. 17, 1925 2,228,232 Hilliard Jan. '7, 1941 2,419,106 Baker et al Apr. 15, 1947 FOREIGN PATENTS Number Country Date 648,635 Germany Aug. 6, 1937 

